The present invention relates to a device for the localized irrigation of agricultural fields, such device comprising a disposable sprinkler line having an outer hose and an inner flexible membrane.
In agriculture, sprinkler pipes used for irrigation purposes are provided with liquid outlet openings distributed along the length of the pipe to provide a nearly uniform wetting of the field to be watered.
Among these, the disposable type is the type which is used for one season only, picked up, possibly together with the plants constituting the cultivation, and destroyed.
The pipes comprising the sprinkling lines are part of a more complete irrigation system, connected to trunk lines from which water is supplied.
The system used generally comprise small cross sectional, sometimes tortuous pipe, designed to create a high enough pressure drop, to cause the liquid to stream out of the pipe in a dropwise fashion (U.K. Pat. Nos. 1,286,538 and 1,484,588). Such devices have the drawbacks that the droppers may be obstructed or that there may be a wide variation in flow rate between individual droppers due to pressure changes, particularly when there are elevational differences.
Other devices used for dropwise irrigation comprise pipes provided in their interior with one or more elastic membranes (U.S. Pat. No. 4,009,832 and Italian Patent Application No. 23,763 A/79). These devices, also suffer from the above mentioned drawbacks, i.e., uneven watering, due to the imperfect sticking of the inner membrane to the inner wall of the pipe.
We have now found, that it is possible to produce a sprinkler line of the disposable type for localized irrigation, which provides even watering and at the same time avoids any dangers of obstructing liquid flow.
It is an object of the present invention to provide a disposable sprinkler line comprising a hose having outlet holes equidistant from each other along the length of the hose and containing, in its interior, flexible membranes sticking to the inner wall of the hose, welded to the inner wall along their whole periphery and capable of forming interstices with the wall in the presence of a water flow. Each outlet hole of the hose is situated inside the interstices formed between the inner wall of the hose and the membrane; the membranes in turn are provided with at least one cut, positioned in a staggered relationship to the outlet holes in the hose.